Importance of Keeping Windows Updated
Microsoft regularly issues patches or updates to solve security problems in their software. The critical updates are the ones you should be concerned about. If these are not applied, it leaves your computer vulnerable to hackers. Service Packs are larger updates which upgrade and fix security problems.
The Windows Update feature built into Windows 98, Me, NT, 2000, and XP can check your PC against a common database of patches. You go to a Microsoft web site and your operating system is checked against critical updates and a suggested list shows for your PC so that you may download and install these. You should do this periodically.
More recent versions of windows have an Automatic Update feature. This is available in Windows 2000, ME, and XP. If you turn on this feature, your PC will check for, download and install critical updates over night. This eliminates the need for you to periodically check for updates.